A badminton racquet, a tennis racquet and the like have a plurality of strings fixed on a racquet frame in a cross manner, thereby forming a mesh structure for hitting a badminton or tennis ball. The string is threaded on the racquet frame with different tensions, which will affect the elasticity of the string and thus change the performance of hitting the ball. Advance preparation is important. If the tension of the string is planned and designed properly, it will enhance the stability of controlling the ball and improve the speed of hitting the ball. It is beneficial for athletes to score well. According to the research, the racquet defines three preferred positions for hitting the ball, which can minimize the impact force transmitted to the hand after hitting the ball, minimize the vibration making the palm and the arm uncomfortable, and maximize the speed or force at which the ball is struck. In order to achieve the best result for the three hitting positions, the tension of each string on the racquet is different.
A conventional racquet stringing machine, as disclosed in Taiwan Utility Model Publication No. M544958, includes a racquet frame clamp device and a string pulling device. The string pulling device moves in a straight direction to tighten the string. The tension of the string is determined by the displacement of the string pulling device. However, the conventional racquet stringing machine is manual operated to thread only one of the positions of the racquet frame during one threading process. Since the racquet stringing machine does not have the ability to identify the current threading position, the operator must do it himself and then pull the string for the required tension at the position, resulting in low production efficiency.
Accordingly, the inventor of the present invention has devoted himself based on his many years of practical experiences to solve these problems.